This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 25 |
| 5 | 75 |
| 6 | 235 |
| 7 | 759 |
| 8 | 2521 |
| 9 | 8555 |
| 10 | 29503 |
| 11 | 103129 |
| 12 | 364547 |
| 13 | 1300819 |
| 14 | 4679471 |
| 15 | 16952161 |
| 16 | 61790441 |
| 17 | 226451035 |
| 18 | 833918839 |
| 19 | 3084255127 |
| 20 | 11451630043 |
| 21 | 42669225171 |
| 22 | 159497648599 |
| 23 | 597950875255 |
| 24 | 2247724108771 |
| 25 | 8470205600639 |